Author Topic: Nichicon Electrolytic Capacitors leaking - common problem? ( Rifa X and Y also)  (Read 2952 times)

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Online free_electron

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no point in griping about capacitors that have gone bad after 30 years of life ... most capacitors have a lifespan of 2000 to 5000 hours ... you do the math.
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Online Fraser

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@Wrapper,

This was the article that I read. Maybe I misinterpreted what it said about X type capacitors and protective devices etc.

https://www.allaboutcircuits.com/technical-articles/safety-capacitor-class-x-and-class-y-capacitors/

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Offline james_s

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no point in griping about capacitors that have gone bad after 30 years of life ... most capacitors have a lifespan of 2000 to 5000 hours ... you do the math.

That's usually the quoted lifetime at the maximum rated temperature and full rated voltage. In practice I would expect the operating life to be considerably longer, but still 30 years is hard to complain about.
 

Online Jay_Diddy_B

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Hi,

I just replaced the Rifa capacitors in an HP 6632A power supply. Like a lot of these supplies you have to remove 80% of the screws in the unit to get access to the bottom of the circuit board. The transformer and the transformer bracket have to be removed.

Overview

[attachimg=1]


The capacitors are toward the rear of the unit

Input Capacitors

[attachimg=2]


Output Capacitors

[attachimg=3]


There are Y rated capacitors on the output.

Parts needed

2x 2200pF 10mm Y caps
2x 4700pF 10mm Y caps
1x 0.22uF 20mm X cap

The unit was around 1995. All the capacitors were cracked.

Regards,
Jay_Diddy_B

« Last Edit: Yesterday at 09:10:24 am by Jay_Diddy_B »
 
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Offline Haenk

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no point in griping about capacitors that have gone bad after 30 years of life ... most capacitors have a lifespan of 2000 to 5000 hours ... you do the math.

That's usually the quoted lifetime at the maximum rated temperature and full rated voltage. In practice I would expect the operating life to be considerably longer, but still 30 years is hard to complain about.

Unfortunately, a) the manufacturers did not expect their products being in use for more than 30 years and therefor didn't plan for easy replacement and b) the failure is only common to certain products (like those wicked RIFA x/y caps), which might be a problem of manufacturing control or general construction, but not a "all caps are dead after 30 years".
 

Online wn1fju

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This is my new hobby - replacing Rifa suppression capacitors.  So far I've replaced 52 of them!  Almost all the X-caps were cracked as were about half of the Y-caps.  Some are particularly hard to get to, for instance when they are right at the AC receptacle and inaccessible without pulling off the back panel.

I bought about 80 non-Rifa suppression capacitors of assorted values a few weeks ago.  I've exhausted most values.  Time for a new order.  I've got a few more HP pieces that I suspect have Rifas.
 

Offline Haenk

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This is my new hobby - replacing Rifa suppression capacitors.

They are simply everywhere. Last I have seen were in a Sony CDP-101, what a surprise. Cracked, of course...
 

Offline syau

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I usually replaced them with Panasonic X1 / Y1 rating due to higher line voltage.
 

Online wraper

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no point in griping about capacitors that have gone bad after 30 years of life ... most capacitors have a lifespan of 2000 to 5000 hours ... you do the math.

That's usually the quoted lifetime at the maximum rated temperature and full rated voltage. In practice I would expect the operating life to be considerably longer, but still 30 years is hard to complain about.

Unfortunately, a) the manufacturers did not expect their products being in use for more than 30 years and therefor didn't plan for easy replacement and b) the failure is only common to certain products (like those wicked RIFA x/y caps), which might be a problem of manufacturing control or general construction, but not a "all caps are dead after 30 years".
I had equipment at my previous job with those Rifa caps in mains filters occasionally exploded starting from about 2015-2016. Those were made in about 2004-2005. So more like 10 years instead of 30. It needs some talent for continuing making this shit for many decades without any fix.
« Last Edit: Yesterday at 05:09:52 pm by wraper »
 

Online free_electron

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This is my new hobby - replacing Rifa suppression capacitors.  So far I've replaced 52 of them!  Almost all the X-caps were cracked as were about half of the Y-caps.  Some are particularly hard to get to, for instance when they are right at the AC receptacle and inaccessible without pulling off the back panel.

I bought about 80 non-Rifa suppression capacitors of assorted values a few weeks ago.  I've exhausted most values.  Time for a new order.  I've got a few more HP pieces that I suspect have Rifas.

don;t forget the ones hiding in many shaffner netfilters inside hp and other equipment ...
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Offline syau

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Those Shaffner which have voltage selection “wheel” never come cheap  :palm:
 

Offline floobydust

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The real issue is the cracking - is the epoxy shrinking or paper absorbing moisture and ballooning out etc. They're old parts, designed before mains transients standards were established. Surely they've been updated in design?

I'd emailed Kemet and told them the PME271's are a POS and why are you still selling them? <crickets>
They're an odd part- "impregnated paper" with no self-healing unless marked "SH". Most datasheets for them say nothing about any self-healing ability. I've never measured any to see if they went low value due to aging.
 

Offline rsjsouza

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I'd emailed Kemet and told them the PME271's are a POS and why are you still selling them? <crickets>.
While there are buyers for these things, there'll be production. Keep in mind that manufacturers might not be able to change designs (qualification, perhaps?) or simply don't care for the future of thr equipment - especially if these sell cheaper that other ones more robust.
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Oh, the "whys" of the datasheets... The information is there not to be an axiomatic truth, but instead each speck of data must be slowly inhaled while carefully performing a deep search inside oneself to find the true metaphysical sense...
 

Online Jay_Diddy_B

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This is my new hobby - replacing Rifa suppression capacitors.  So far I've replaced 52 of them!  Almost all the X-caps were cracked as were about half of the Y-caps.  Some are particularly hard to get to, for instance when they are right at the AC receptacle and inaccessible without pulling off the back panel.

I bought about 80 non-Rifa suppression capacitors of assorted values a few weeks ago.  I've exhausted most values.  Time for a new order.  I've got a few more HP pieces that I suspect have Rifas.

How are we going to compete?


1) Total number changed?
2) Total weight of Rifa X and Y caps changed?
3) Total number of uF changed?
4) Total number of screws that have to be removed to get to the most difficult little ba$tard?

 :-//   :popcorn:

Jay_Diddy_B
« Last Edit: Today at 01:14:00 am by Jay_Diddy_B »
 
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Offline james_s

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While there are buyers for these things, there'll be production. Keep in mind that manufacturers might not be able to change designs (qualification, perhaps?) or simply don't care for the future of thr equipment - especially if these sell cheaper that other ones more robust.

In most cases there is no business reason for them to care. The capacitors we are talking about are ~30 years old. How many companies support anything once it is that old? The other day I worked on a ~12 year old $40,000 veterinary ultrasound machine, the manufacture wanted nothing to do with it and refused to provide any support, the medical equipment repair vendors turned it down too because it's "too old", so I fixed it. Once a piece of equipment is out of production and out of warranty most companies prefer if it fails sooner than later.

And these caps, at least in 120V land are not that big of a deal. I've had a grand total of ONE of them burn up, I'm sure I've got lots of them in various gear, I've never replaced one preventatively, ever. If any more of them burn up I'll replace them after the fact.
 

Online wn1fju

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Jay_Diddy_B writes, "How are we going to compete? Number, weight, etc... "

This is not a competition I am eager to win!  With Rifa capacitors, everybody eventually loses.

I have gone through most of my pieces, but there are a few more HP pieces that I know have Rifas and a few more that I suspect also do.  Why is it that those pieces are on the bottom of my stacks with 10 heavy pieces above them.  My back already hurts from moving a ton of equipment around.

Photo shows the carnage so far... 57 Rifa caps preemptively replaced.  Many of them look far worse in the picture than I originally found them.  This is because I often found it easier to remove the cap from the component side (when getting to the foil side looked like a pain in the butt) and so were chipped or cracked or mauled by rocking them with pliers until they pulled free.

Most of the casualties were from HP and Tektronix pieces in the 1980s and early 1990s.  The worst offender was the HP 8160A pulse generator with nine Rifas, followed by the HP 6621A power supply with seven Rifas and the HP 8080A word generator with six Rifas. 

Whereas most of the Rifas are lurking right near the AC jack on the back panel, there were a few cases where HP used them in "non-standard" places, like after the diode bridge in the switching power supply of the HP 3764A digital transmission analyzer or on the output of the HP 6621A power supply.

I didn't do anything with the sealed line filter modules found in many pieces.  I know Schaffner has a bad reputation, but replacing Rifas at about 35 cents a pop (no pun intended) is a lot nicer than $30/each for a line filter. 

I will probably end up with a count of about 70 Rifa caps replaced.  Maybe I will glue them all to a piece of cardboard, frame it, and hang it on the wall.

 


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